Question 1

According to VSEPR theory, what is the electron group geometry around the central atom in $$\mathrm{CO_2$}$$, and what is the expected bond angle?

Accepted Answer

Linear, $$180^\circ$$

Question 2

Which of the following statements best explains why lone pairs cause bond angles to be smaller than expected in molecules like $$\mathrm{NH_3$}$$ and $$\mathrm{H_2O}$$?

Accepted Answer

Lone pairs occupy more space on the central atom, increasing repulsion and decreasing bond angles.

Question 3

A molecule of $$\mathrm{$$BrF_3$$}$$ has five electron groups around the central atom. What are its electron geometry and molecular geometry, respectively?

Accepted Answer

Trigonal bipyramidal, T-shaped

Question 4

Which of the following molecules is nonpolar?

Accepted Answer

$$\mathrm{$$XeF_4$$}$$

Question 5

Place the following in order of increasing X-Se-X bond angle, where X represents the outer atoms: $$\mathrm{$$SeO_2$$}$$, $$\mathrm{$$SeCl_6$$}$$, $$\mathrm{$$SeF_2$$}.$$

Accepted Answer

$$\mathrm{$$SeCl_6$$} \u003c \mathrm{$$SeF_2$$} \u003c \mathrm{$$SeO_2$$}$$

Question 6

Which of the following best describes the molecular geometry of $$\mathrm{NH_3$}$$?

Accepted Answer

Trigonal pyramidal

Question 7

A molecule has four electron groups and two lone pairs on the central atom. What is its molecular geometry?

Accepted Answer

Bent

Question 8

Which of the following molecules has a bond angle closest to $$109.5^\circ$$?

Accepted Answer

$$\mathrm{CH_4$}$$

Question 9

Why do lone pairs in a trigonal bipyramidal electron geometry preferentially occupy equatorial positions?

Accepted Answer

Equatorial positions have less repulsion because they are farther apart from each other than axial positions.

Question 10

Which of the following best describes the electron geometry and molecular geometry of $$\mathrm{SF_4$}$$?

Accepted Answer

Trigonal bipyramidal, seesaw

Question 11

A molecule has six electron groups around the central atom, two of which are lone pairs. What is the molecular geometry?

Accepted Answer

Square planar

Question 12

Which of the following molecules is expected to have the smallest bond angle?

Accepted Answer

$$\mathrm{H_2O}$$

Question 13

Which of the following is a requirement for a molecule to be polar?

Accepted Answer

It must have polar bonds and an unsymmetrical shape.

Question 14

Which of the following best describes the molecular geometry of $$\mathrm{$$XeF_4$$}$$?

Accepted Answer

Square planar

Question 15

A molecule has three electron groups and no lone pairs on the central atom. What is its electron geometry and molecular geometry?

Accepted Answer

Trigonal planar, trigonal planar

Question 16

Which of the following best explains why $$\mathrm{CO_2$} is $$nonpolar even though it contains polar bonds?

Accepted Answer

The molecule is linear, so the bond dipoles cancel each other out.

Question 17

Which of the following molecules has a net dipole moment?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 18

A patient is exposed to $$\mathrm{CO_2$}$$ gas. Based on its molecular geometry, what is the bond angle between the oxygen atoms, and how does this relate to its ability to dissolve in water?

Accepted Answer

$$180^\circ$$; nonpolar, so it dissolves poorly in water

Question 19

Which of the following best describes the effect of a double bond on bond angles in a molecule like formaldehyde ($$\mathrm{CH_2O}$$)?

Accepted Answer

A double bond increases the bond angle adjacent to it due to greater electron repulsion.

Question 20

Which of the following is the correct order of repulsive force interactions between electron groups on a central atom?

Accepted Answer

Lone pair–lone pair \u003e lone pair–bonding pair \u003e bonding pair–bonding pair

Chemical Bonding: Molecular Shapes and VSEPR Theory

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